diff --git a/src/lib/spa-route.test.ts b/src/lib/spa-route.test.ts
index 1a731fc..a56db60 100644
--- a/src/lib/spa-route.test.ts
+++ b/src/lib/spa-route.test.ts
@@ -4,6 +4,7 @@ import { isSpaRoute } from './spa-route';
 describe('Reader SPA route boundary', () => {
   it.each([
     '/about',
+    '/app',
     '/privacy',
     '/sample',
     '/library',
diff --git a/src/lib/spa-route.ts b/src/lib/spa-route.ts
index 990977f..c8b2eb5 100644
--- a/src/lib/spa-route.ts
+++ b/src/lib/spa-route.ts
@@ -1,5 +1,6 @@
 const EXACT_SPA_ROUTES = new Set([
   '/about',
+  '/app',
   '/privacy',
   '/welcome',
   '/sample',
diff --git a/src/router.tsx b/src/router.tsx
index 45189a2..e8a4cee 100644
--- a/src/router.tsx
+++ b/src/router.tsx
@@ -1,5 +1,5 @@
 import type { ComponentType } from 'react';
-import { createBrowserRouter } from 'react-router-dom';
+import { createBrowserRouter, Navigate } from 'react-router-dom';
 
 import RootLayout from './RootLayout';
 
@@ -27,6 +27,7 @@ export const router = createBrowserRouter([
     hydrateFallbackElement: <RouteLoading />,
     children: [
       { path: 'about', lazy: () => lazyPage(() => import('./pages/AboutPage')) },
+      { path: 'app', element: <Navigate to="/library" replace /> },
       { path: 'privacy', lazy: () => lazyPage(() => import('./pages/PrivacyPage')) },
       { path: 'welcome', lazy: () => lazyPage(() => import('./pages/WelcomePage')) },
       { path: 'sample', lazy: () => lazyPage(() => import('./pages/SamplePage')) },